Muckno Lake (Irish: Loch Mucnú),[1] also known as Lough Muckno, is a freshwater lake in the northeast of Ireland.

It is located in County Monaghan beside the town of Castleblayney.

Muckno Lake measures about 4 km (2.5 mi) long and 1.0 km (0.6 mi) wide.

It flows out to the Clarebane River, which connects the lake to nearby Lough Ross.

[2] Fish species in Muckno Lake include European perch, common roach, common bream, gudgeon, northern pike and the critically endangered European eel.